Acrylonitrile-butadiene-styrene copolymer resin (hereinafter referred to as ‘ABS resin’) is a resin in which a copolymer of styrenic monomer and acrylonitrile monomer grafted to butadiene rubbery polymer (hereinafter referred to as ‘g-ABS’) is dispersed in a matrix of styrene-acrylonitrile copolymer resin (hereinafter referred to as ‘SAN’). ABS resin has a good balance of properties such as processability, impact strength, rigidity, and melt strength, in addition to excellent colorability and gloss. Thus ABS resin has been widely used for automobile goods, household electric/electronic appliances and office automation equipment which require a good appearance. However, when ABS resins are used for internal or external parts of electric/electronic goods such as blenders, washing machines, fans, and the like on which repeated stress caused by driving a motor is exerted, it is necessary for these parts to resist such stress and to remain durable for extended use. Thus they are required to have good impact resistance in addition to chemical resistance to strong chemicals such as acetic acid or diesel oil.
Polyester resins typically have a structure including short chains, and thus may not bend easily. Accordingly, polyester resins can have good rigidity, electrical properties, weather resistance and heat resistance, and the tensile strength of polyester resins may not be affected even after long term exposure to high temperatures. Further, crystalline polyester resins have good resistance to various chemicals such as diesel oil.
However, properties of crystalline polyester resins such as processability and impact resistance can degrade when they are exposed to acid or alkali at high temperatures over a period of time. Thus, reinforcing agents such as glass fiber can be added to the polyester resins when polyester resins are employed as a structural material. If reinforcing agents are not added, it is difficult to use polyester resins as injection molded structural materials. In addition, polyester resins can have low melt strength, and thus it can be difficult to form extrusion molded polyester products other than films, such as thick sheets or pipes.
Recent attempts to prepare thermoplastic resins having good chemical resistance and impact resistance have included alloying a polyester resin with an ABS resin. However, the alloy has a disadvantage in that it is difficult to impart good extrudability to the alloy due to its low melt strength.